Detection device commonly used for video/audio interface outlet and earphone line outlet

ABSTRACT

A detection device and method commonly used for a video interface outlet and earphone line outlet is used to allow the detection device to detect whether a three- or four-terminals plug is inserted in the outlet. The detection device detects whether the impedance value of the video output terminal of the plug is larger than the preset value. If yes, the detection device control a video signal output terminal to output a video signal. If the impedance is not larger than the preset value, the detection device then controls the video signal output not to output a video signal and only to output an audio signal.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a video/audio outlet in a video/audioplayer, and more particularly to a detection device and method commonlyused for video and audio outlets in a carry type recorder/player orcarry type player.

2. Description of Related Art

The video/audio output interface of a general carry type videorecorder/player and video player is shown in FIG. 1. The interfacecomprises a four-terminals outlet 10 and a corresponding circuitstructure 20. The outlet 10 includes a ground terminal 11, video outputterminal 12, first audio output terminal 13 and second audio outputterminal 14, which are contacted respectively with a ground terminal 31,video input terminal 32, first audio input terminal 33 and second audioinput terminal 34 of the video/audio four-terminals plug 30 shown inFIG. 2. The first audio output terminal 13 is connected to a push rod15. The push rod 15 can be pushed simultaneously to separate a detectionline 16 from a ground line 17 when the plug 30 is inserted to touch thefirst audio output terminal 13. A video signal output terminal 21,second audio signal output terminal 22, first audio signal outputterminal 23 and plug detection terminal end 24 of the circuit structure20 are communicated respectively with the video output terminal 12, thesecond audio output terminal 14, the first audio output terminal 13 andthe detection line 16 of the outlet 10.

At present, a general video/audio device has an earphone three-terminalsoutlet and video four-terminals outlet respectively. Please refer toFIGS. 2 and 3. A three-terminals earphone plug 40 and four-terminalsvideo plug 30 must be inserted in a commonly used four-terminals outletin order to reduce the volume of video/audio device that appears smallerand smaller. The most commonly used method is to revise the structure ofa outlet so as to be able to judge what kind of plug is inserted when itmust be used commonly. Otherwise, a plug must be furnished with multipleof respective output lines. But, if a standard earphone plug with a 3.5φ or 2.5 φ diameter is still be used, the outlet revise is impractical.The only way we can do is to use the four-terminals outlet of thestandard insertion holes, and then to operate in cooperation with theoutput mode of the manual operation system. For example, a video/audiodevice with such as the four-terminals outlet 10 shown in FIG. 1 for thecommon output of a video output and audio output is already existed inthe market. But, a user must choose whether to output a video signalsimultaneously by using the manual operation system. The user mustchoose not to output a video signal and shut off an in built horn devicewhen the three-terminals earphone outlet 40 is inserted. On the otherhand, the user must not only choose outputting a stereo audio signal andshutting off the in built horn device but also allowing the system tooutput a video signal if the four-terminals video plug 30 is inserted.The operation for switching output modes mentioned above rather wastestime, it is inconvenient for a user that is not familiar with the outputmodes switching. The first audio input terminal 41 and the second audioinput terminal 42 of the plug 40 are contacted respectively with thefirst audio output terminal 13 and the second audio output terminal 14when the plug 40 is inserted. But, the ground terminal 43 of the plug 40is contacted at the same time with the ground terminal 11 and the videooutput terminal 12 of the outlet 10. A video signal is transmittedcontinuously to the video output terminal 12 and consequently to theground terminal 11 if the video signal output is not stopped. This isonly wastes electricity but also might damage the parts in a circuit.

SUMMARY OF THE INVENTION

The main object of the present invention is to provide a detectiondevice and method commonly used for a video interface outlet andearphone line outlet, judging what kind of a plug is inserted andoutputting a corresponding signal in order to cause a four-terminalsoutlet to be used more conveniently and to prevent parts in a circuitfrom being damaged by detecting a different impedance at a video outputterminal of a four-terminals outlet while a four video terminal andthree-terminals earphone plug are inserted.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention can be more fully understood by reference to thefollowing description and accompanying drawings, in which:

FIG. 1 is a schematic view of a general video/audio output interface;

FIG. 2 is a schematic view of a general four-terminals video/audio plug;

FIG. 3 is a schematic view of a general three-terminals earphone plug;

FIG. 4 is a flow chart of a detection method according to the presentinvention;

FIG. 5 is a schematic view showing a connection between a video/audiooutput interface and a detection device of the present invention; and

FIG. 6 is a schematic view showing a video/audio output control circuitconnected to a detection device of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIG. 4. A detection method according to the presentinvention allowing video/audio interface outlet and earphone line outletto be commonly used comprises the following steps: steps 401 and 402allowing a detection device to detect whether a three- or four-terminalsplug is inserted in a four-terminals outlet, continuing to detect if theplug is not inserted, or entering a next step; steps 403 and 404allowing the detection device to detect whether an output impedance ofthe video/audio output terminal of the four-terminals outlet is largerthan a preset value, entering a step 405 to allow the detection deviceto control a video signal output terminal to output a video signal ifthe answer is yes, or entering a step 406 to allow the detection deviceto control the video signal output terminal not to output a video signalif the answer is no.

Please refer to FIGS. 1, 2 and 3. The detection device can detect theinsertion of the four-terminals plug 30 of this video/audio connectionline when it is inserted owing that the input terminal of a videoreceiving device has an input impedance 75Q or a unlimited large opencircuit impedance is existed when the video/audio connecting line 35 isnot connected to the video receiving device. Both the video outputterminal 12 and the ground terminal 11 are contacted with the groundterminal 43 and communicated one another to cause the output impedanceof the video output terminal 12 to become smaller when thethree-terminals earphone plug 40 is inserted; the insertion of thethree-terminal earphone plug 40 can be detected so as to control thevideo signal output terminal 21 not to output a video signal when asmaller output impedance of the video output terminal 12, such as avalue is smaller than 60 Ω, is detected by the detection device.

Next, please refer to FIG. 5. A detection device 50 comprises amicroprocessor 51 (such as Microprocessor ARM7), first, second switchchips 52, 53, a transistor 54 and corresponding resistors R2, R3 and R4.The microprocessor 51 are connected respectively to the plug detectionterminal 24 shown in FIG. 1, control signal input terminals 55, 56 ofthe first, second switch chips 52, 53 and signal output terminal 57 ofthe transistor 54. The first and second switch chips 52 and 53 arefurther connected respectively to the transistor 54 through thecorresponding resistors R2, R3 and R4. A detection-use power supplyinput terminal 58 is connected to the first switch chip 52. The powersupply input terminal 58 is communicated respectively to the transistor54 and the second switch chip 53 through the corresponding resistors R2,R3 and R4 when the first switch chip 52 is opened. The second switchchip 53 is further connected to the video output terminal 12 of the plug10. The microprocessor 51 emits a signal to open the first and thesecond switch chips 52 and 53 from the control signal input terminals 55and 56 at approximate 0.3 seconds after it detects the message that aplug is inserted in the plug detection terminal 24 to causedetection-use power to transmit to the transistor 54 and the secondswitch chip 53 and to cause the second switch chip 53 to allow thesignal output terminal 57 of the transistor 54 to feedback the levelstate of the output impedance to the microprocessor 51 to discern thetype of the inserted plug according to the output impedance value of thevideo output terminal 12. Next, take FIGS. 2 and 3 into consideration.The output impedance is caused to become smaller and consequently theoutput impedance becomes smaller so as to cause the signal outputterminal 57 of the transistor 54 to be at a high voltage level becauseboth the video output terminal 12 and the ground terminal 11 arecontacted with the ground terminal 43 and communicated with one anotherwhen the three-terminals earphone plug 40 is inserted. The outputimpedance does not become low or has a unlimited open circuit impedanceso that it is a high value to cause the signal output terminal 57 of thetransistor 54 to be at a low voltage level owing to the video outputterminal 12 and the ground terminal 11 are not communicated when thefour-terminals video/audio plug 30 is inserted.

Please refer to FIGS. 5 and 6. The transistor 51 is further connected toa control signal input terminal 61 of a third switch chip 60, and theknown third switch chip 60 is further connected to the power supplyterminal of the known video signal amplifier 70.

The microprocessor 51 emits a control signal to the third switch chip 60to cause the third switch chip 60 to control the amplifier 70 to outputa video signal or not to output a video signal to the video signaloutput terminal 21 when the microprocessor 51 detects that the signaloutput terminal 57 of the transistor 54 is at a high voltage level or ata low voltage level. Meanwhile, the microprocessor 51 emits a controlsignal to close the first and the second switch chips 52 and 53 to saveelectricity and to prevent the video signal from being interrupted whenit is output from the amplifier 70. The first, second and third switchchips 52, 53 and 60 of the present invention can be switch chips with aserial number UMC2N.

The present invention can automatically detect that a three-terminalsearphone plug or four-terminals video/audio plug is inserted in afour-terminals video/audio outlet, and automatically control a videosignal output terminal whether to output a video signal. A user does notneed to choose a system output mode manually so that it is more simple,convenient and speedy on operation. Also, the parts in a system circuitare not damaged even if the user forgets or is unable to choose a properoutput mode. A user does not need to operate an output mode manuallyaccording to the present invention, a four-terminals outlet that iscompatible with a standard three-terminals earphone plug can be held, anoperation is simplified, a wrong operation can be removed and the damageto parts in a system can be prevented.

The detection device according to the present invention only needs twoswitch chips, a transistor and three corresponding resistors, and canattain a very good effect even if its structure is simple and its costis low. It is noted that the detection device and method commonly usedfor a video interface outlet and earphone line outlet described above isthe preferred embodiment of the present invention for the purpose ofillustration only, and are not intended as a definition of the limitsand scope of the invention disclosed. Any modifications and variationsthat may be apparent to a person skilled in the art are intended to beincluded within the scope of the present invention.

1. A detection method commonly used for a video interface outlet andearphone line outlet, comprising the following steps: (1) allowing adetection device to detect whether a plug is inserted in afour-terminals outlet, if no, continuing detecting; otherwise, enteringa next step; (2) allowing said detection device to detect whether animpedance value of a video output terminal of said four-terminals outletis larger than a preset value, if yes, causing said detection device tocontrol said video output terminal to output a video signal; if no,causing said detection device to control said video signal outputterminal not to output a video signal.
 2. The method according to claim1, wherein said detection device is connected to a plug detectionterminal and video output terminal of said four-terminals outlet; saiddetection device emits a control signal to cause said video signaloutput terminal to output a video signal or not to output a video signalaccording to an output impedance value of said video output terminalwhen said detection device detects a message that a plug is inserted insaid plug detection terminal.
 3. The method according to claim 2,wherein said detection device comprises a microprocessor connectedrespectively to said plug detection terminal of said four-terminalsoutlet, control signal input terminals of first, second and third switchchips and a signal output terminal of a transistor; said first andsecond switch chips are further connected respectively to saidtransistor through corresponding resistors; a detection-use power supplyinput terminal is connected to said first switch chip; said power supplyinput terminal communicates said transistor and said second switch chiprespectively through said corresponding resistors when said first switchchip is opened; said second switch chip is further connected to a videooutput terminal of said outlet; said microprocessor emits a signal toopen respectively said first switch chip and said second chiprespectively through said control signal input terminals when saidmicroprocessor detects a message the a plug is inserted in said plugdetection terminal; said detection-use power is caused to transmit tosaid transistor and said second switch chip, and said second switch chipis caused to rely on an output impedance value of said video outputterminal to cause a signal output terminal of said transistor tofeedback a level state of said output impedance to said microprocessor;said microprocessor then emits a control signal to said third switchchip to cause said third switch chip to control an amplifier to output avideo signal or not to output a video signal to said video signal outputterminal.
 4. The method according to claim 3, wherein saidmicroprocessor then emits a control signal to said third switch, and inthe meantime, emits a control signal to close said first and secondswitch chips.
 5. A detection device commonly used for a video interfaceoutlet and earphone line outlet, comprising a detection device connectedrespectively to a plug detection terminal and video output terminal of afour-terminals outlet; thereby, said detection device can discern thetype of an inserted plug according to an output impedance value of saidvideo output terminal when said detection device detects a message thatsaid plug is inserted in said plug detection terminal.
 6. The deviceaccording to claim 5, wherein said detection device comprises amicroprocessor connected respectively to said plug detection terminal ofsaid four-terminals outlet, control signal input terminals of first andsecond switch chips and a signal output terminal of a transistor; saidfirst and second switch chips are further connected respectively to saidtransistor through corresponding resistors; a detection-use power supplyinput terminal is connected to said first switch chip; said secondswitch chip is further connected to a video output terminal of saidoutlet; whereby said microprocessor emits a signal to open respectivelysaid first switch chip and said second chip respectively through saidcontrol signal input terminals when said microprocessor detects amessage that a plug is inserted in said plug detection terminal; saiddetection-use power is caused to transmit to said transistor and saidsecond switch chip, and said second switch chip is caused to rely on anoutput impedance value of said video output terminal to cause a signaloutput terminal of said transistor to feedback a level state of saidoutput impedance to said microprocessor so as to know the type of saidinserted plug.
 7. The device according to claim 6, wherein saidmicroprocessor is further connected to a control signal input terminalof a third switch chip, said third switch chip is further connected to apower supply of a video signal amplifier so that said microprocessoremits a control signal to said third switch chip to cause said thirdswitch chip to control said amplifier to output a video signal or not tooutput a video signal when said microprocessor detects a signal outputterminal of said transistor is at a high voltage level or at a lowvoltage level.